The prime minister is seeking public assurances, or even possible tweaks to the deal, as she struggles to gather enough support among UK MPs to put it to a vote in Parliament.

On Monday she was forced to abandon a planned vote on the deal she has agreed with the EU after more than 100 Conservative MPs and the Democratic Unionist Party, which props up her minority government, committed to voting it down.

May will meet with European Council President Donald Tusk and Irish Taoiseach Leo Varadkar today ahead of addressing a dinner of EU leaders.

So what hopes does May have of securing enough concessions from the EU to save her Brexit deal and the future of her government?

What's the problem?

YouTube May needs the vast majority of Conservative MPs as well as the DUP to support the Brexit Withdrawal Agreement in order to have a realistic chance of getting it through Parliament.

However, more than 100 Conservative MPs and every single DUP MP have vowed to reject it. This is largely due to the inclusion of the so-called Brexit backstop, which is designed to make sure there is no hard border on the island of Ireland no matter what happens after Brexit.

According to the Withdrawal Agreement, if by the end of the 21-month post-Brexit transition period a new UK-EU free trade deal including sufficient protections for the island of Ireland is not ready, the backstop will be activated.

In this scenario, the whole of the UK will remain in the EU's Customs Union, and consequently be stuck with an array of EU trade and customs rules and regulations, while Northern Ireland alone will remain in parts of the single market.

Conservative MPs hate this because as things stand, there is no fixed end date for the backstop, and the UK cannot make the unilateral decision to leave. In theory, it could be stuck in this half-in, half-out state indefinitely.

The DUP hates it because it would create new border checks between Northern Ireland and Great Britain. This, they argue, would represent an unacceptable undermining of Northern Ireland's place in the UK.

Swathes of Conservative MPs and every single DUP MP is set to vote against the deal until these issues are addressed.

And even if May can somehow manage to get a deal through parliament on these terms, then the DUP has promised to withdraw their support from her government altogether meaning a vote of no confidence in parliament and a possible general election could be on the cards.

Is there a solution?

Arlene Foster, leader of the DUP. Clodagh Kilcoyne/Reuters

May told hostile MPs on Wednesday that she would seek "legally binding solutions" to the controversial backstop when she meets leaders in Brussels— but what does that mean?

It's pretty nebulous language but what it means is May will ask the EU to tweak the Brexit deal to include clear, written assurances that it will try its best to avoid the backstop coming into effect and if it does, it will only be temporary.

However, while the EU has said it is open to providing some assurances, it is also clear that the substance of the legally binding Withdrawal Agreement cannot be renegotiated. European Commission President Jean-Claude Juncker, European Council President Donald Tusk, and leaders of the European Parliament have repeatedly made this clear.

This likely means that the best May can hope to get from the EU is an accompanying statement — or an 'addendum' — spelling out its commitment to finding alternative arrangements to the backstop.

A government source told Business Insider this week that work on what this statement could look like secretly got underway in Westminster weeks ago in anticipation of a backlash from pro-Brexit MPs.

The BBC's Adam Fleming reports that the statement could commit the EU to negotiating a free trade deal with the UK as quickly as possible in order to avoid the backstop being in place for years after Brexit day. This could include an explicit date by which the EU will aim to negotiate a new trade deal with the UK, according to other reports.

Will this work?

Getty The DUP has been clear that only fundamental changes to the legally binding Withdrawal Agreement will be acceptable to them. Otherwise, they say, any tweaks to the deal will merely be aspirational, and have no legal effect.

Based on the EU's current position, such changes are simply not forthcoming.

A statement of intent to accompany the Brexit deal might win around a handful of Conservative MPs but the staunch Brexiteers who tried to oust May this week are unlikely to be convinced. And without support from other parties, May need only suffer a tiny rebellion from Conservative MPs to lose her majority in parliament.

Liam Fox, the International Trade Secretary, said earlier this week than even Cabinet ministers might not support the revised deal if it doesn't come with changes to the legal details of the backstop.

In reality, unless the EU's position changes dramatically, what May brings back to Westminster from Brussels is unlikely to satisfy the demands of her critics, and a parliamentary defeat for her deal will still await her.

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